OUMF seeks a definitive solution to generic TVR heat management issues on a 1990 350i using Zircotec Thermohold and ZircoFlex Gold

​Who are Zircotec?
Zircotec Ltd is a world leader in heat management, specialising in high temperature coatings and heat barrier solutions. Originally part of the UK Atomic Energy Authority, Zircotec’s expertise lies in thermal barrier technologies initially developed for the nuclear industry. Zircotec is known for its plasma-sprayed ceramic coating materials that provide thermal and ​abrasive resistance. Their core products, such as...

 Thermohold and Zircoflex are particularly suitable for automotive exhaust systems, and Zircotec support has brought OUMF students great benefits on their competition car practical projects.
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What is Zircotec Thermohold?
A thin, lightweight plasma-sprayed ceramic coating effectively ‘welded’ to the substrate – most commonly metal exhaust systems and components – which contains the heat within the hot exhaust gases, substantially reducing the radiated heat by around 33%. It thus reduces heat damage to components in close proximity, protects against corrosion (rather than promoting it, like exhaust wraps), lowers under-bonnet and intake charge temperatures, and allows handling of exhaust components much faster during pits stops/servicing in motor sport events. 

What is ZircoFlex Gold?
ZircoFlex Gold is a gold-backed heat shield material utilising ceramic mosaic patterns that allow otherwise inflexible ceramics, when studded on to foil, to be folded and moulded around complex shapes and curves. This flexibility allows it to be placed anywhere on the car. It is also very light, weighing in at 0.560kgm3. This, coupled with a thickness of between just 0.25mm (ZircoFlex 1) to 0.85mm (ZircoFlex 3) ensures an effective heat management solution with minimal weight gain, which is so important in motorsport applications. The attractive gold finish is not simply aesthetic; both the contrast and reflected light it provides can help make other components around it easier to locate and inspect. 

Why Zircotec?
Our background research on the OUMF 1990 TVR 350i practical project revealed that one of the top concerns amongst owners of this model, and most other models of TVR - reflected on the internet and particularly on TVR forums - was about the damage and corrosion caused to the chassis and body by the radiant heat from the exhaust system. Since the exhaust is invariably mounted very close to the chassis on these cars, the amount of thermal energy created by the big V8 engines and given off by the exhaust systems, chars and burns the paint off the chassis and blisters the fibreglass bodywork. Also, especially on a warm summer day, the heat radiating through the transmission tunnel can also make the cabin a very hot and unpleasant place to spend anytime in a traffic jam! Given the chassis protection on TVRs is generally regarded as poor in the first place, the heat cycles from the exhaust frequently accelerate the onset of corrosion on chassis members on which the paint has been burned away, which, coupled with salted roads, exacerbates the problem. There were stories of owners having to completely replace their chassis after as little as 8 years from new. Others who factored in repainting large areas of the chassis as part of the cars annual service! The original powder coating burns, cracks and flakes off, leaving the bare steel chassis open to attack from the unforgiving British climate, as seen in the two photos that follow. 
One might have expected that TVR would have acted on customer feedback to address this evident issue, but it appears that the factory did not regard improvements in coatings, shielding or general heat management as a priority. ​

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Zircotec MD Terry Graham was well aware of these perennial TVR problems and pledged Zircotec’s full support to the students’ project with the best and most appropriate products and his invaluable advice.

With his backing, we set about finding a definitive solution to this common problem, for the benefit and longevity of not just the current OUMF project, the 1990 350i, but the many owners suffering from the same issues. We initially inspected the length and breadth of the chassis, and tapped all the metal tubes with hammers to establish its integrity. The previous owner had clearly repainted the chassis shortly before laying the car up for 20 years, so fortunately, while there were areas of surface rust, (as expected, mostly near the run of the exhaust) it all rang true, and no welding was required. Nevertheless, as a first step, we wanted to recoat it with a known and dependable high quality, heat-resistant paint, and from long experience there is none better than Rustbuster’s Epoxy Mastic 121. The surface rust and paint was quickly dispatched with our trusty Monti MBX Bristle Blaster, leaving the surface of the metal clean and well-keyed for the application of two coats of Epoxy Mastic paint – in white to match the original powder coating.

While this process was in train, the full stainless steel exhaust system was given the great benefit of Zircotec’s Thermohold plasma coating - in their most popular ‘Graphite’ colour – to reduce radiant heat by up to 33%. We have found this the best shade to resist and conceal surface markings left by mechanics with dirty hands, which are inevitable over time, especially on a competition car subject to constant disassembly and maintenance. The exception were the two tailpipe finishers which were finished in Zircotec Thermohold silver. By the time the beautifully coated system returned, the chassis was painted, and so the exhaust system could be assembled and mounted on the car. White board markers were then used to highlight all the vulnerable areas of the chassis and bodywork close to its run in order to deploy the ZircoFlex Gold reflective ceramic foil to the greatest effect. We felt that this ‘belt and braces’ approach i.e. the combination of heat containment by the Thermohold on the pipes, coupled with the application of reflective ZircoFlex to the areas of the chassis and body in close proximity to the exhaust - all underpinned by excellent heat resistant Epoxy Mastic paint – was going to provide the best, long-lasting result. We know that piecemeal attempts using only one or two of these components had failed over time. We have every confidence that these measures will ensure the best heat management, so saving the chassis from future substantial rust repairs - or possibly even the need for a replacement chassis as many owners have found to their much greater cost.

For reference, the two photos are of Jim Green’s TVR Tuscan featured on Pistonheads TVR General Forum in 2009 when the car was less than 10 years old. 
To underline the problem, his car had covered just 19,000 miles at this point, and never been driven in the rain or taken on track - so had had no contact with road salt either – which makes these photos even more depressing! The areas affected by the heat are noticeable since the unaffected parts of the chassis retain the white powder coating of the factory finish. 
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ZircoFlex - Application Process
The application process is very simple, as ZircoFlex is backed with a 3M self-adhesive coating. All that is needed is to cut the sheet to shape using household scissors or a craft knife, peel off the protective backing and stick the ZircoFlex to whatever area needs heat protection – obviously with the proviso that the surface is sound and appropriated cleaned/degreased before application. Our experience is that the thicker grades of ZircoFlex gold were more suited to areas with less complication in shape or sharp radii. In these areas a heat gun was used to gently warm the adhesive and the substrate, and hand rollers ensured the best bond possible.

The two photos below show the process close to completion. We applied ZircoFlex from the engine bay all the way to the back of the car, following the path of the exhaust. We are confident that our chassis and areas of the body like the footwells and tunnel will be fully protected from both heat and other corrosive elements.

I would like to conclude this report by giving OUMF’s great thanks to Terry Graham, MD of Zircotec, for his interest in helping the students address a long-standing problem faced by so many TVR owners and his generous support in providing the most cutting edge products currently available to engineer a definitive solution. It has helped us protect our TVR project, and to learn a great deal about the many facets of heat management in our journey through the process.

Lastly, there is another aspect of heat management, which we have not overlooked, which is the considerable heat actually generated by the V8 engine itself and controlled by the cooling system. When the engine is installed after its rebuild - with kind support from THINK Automotive, ARP, Kent Cams, EnginePartsUK, NGK, Real Steel, Richard Moore, and Dom Trickett at TVR Power -  we will be seeking to optimise its cooling with the help of Davies Craig and their state of the art electric pump, fans and controllers, and a super-efficient, bespoke aluminium radiator from Radtec...so watch this space!

- Written by Kit Tiernan (First Year: BENGH-MF)